SG194462A1

SG194462A1 - Method for the preparing surfaces

Info

Publication number: SG194462A1
Application number: SG2013075882A
Authority: SG
Inventors: Christophe Navarro; Stephanie Magnet; Xavier Chevalier; Raluca Tiron
Original assignee: Arkema France; Commissariat Energie Atomique; Inst Polytechnique Bordeaux
Priority date: 2011-04-15
Filing date: 2012-04-13
Publication date: 2013-12-30
Also published as: KR101953928B1; WO2012140383A3; JP2014517763A; EP2696993A2; AU2012241655A1; ES2730708T3; KR20140007458A; KR101828231B1; CN103842097A; EP2696993B1; JP5876567B2; WO2012140383A2; US20140127418A1; FR2974094A1; KR20170064002A; CN103842097B; SG10201804980YA

Abstract

Method for preparing surfaces5The invontlon relates to a. new surface bmeoaration method using molecules comprising at least one covalent. bond. which. aloes yime to free radicals when the molecule is activated thermally, by orgabic or inorganic redox, photochemically,M ny plasma, oy shear or else under the influence ot ionizing rtadt aM ion .

Description

S1-

Method for preparing surfaces

The invention relates Lo a new surface preparation method using molecules comprising at least one covalent bond which gives rise to free radicals when the molecule ig activated thermally, by organic or inorganic reduction-oxidation, photochemically, by plasma, by shear or else under the influence of ionizing radiation.

The invention also relates to the use of this new preparation method, more particularly in applications for controlling the surface energy of a substrate, For example, 1 may allow the structuring of 2 block copolymer which is subsequently applied, but the invention also allows the treatment of surfaces for enhancing the printability of

Lnks cor of paint, the wettability, the weathering or ageing resistance, the adhesion, Cle biccompatibiiity, the prevention of migration of inks, and the prevention of deposits of proteins, soiling or moulds,

The use, by virtue of their CADECITY LO UNGS go nanostructuring, of block covolyvmers in the fields of slecironics or optoelectronics is now wall known. lt ig possible more particularly Lo structure Lhe arrangement of the blocks constituting the copolymers on scales oi smaller than 50 am.

The desired structuring {for example, generation of domains perpendicular to fhe surface), however, redulres the preparation of the substrate to which the block copolymer ig applied, for the purpose of controlling the surfaces energy. Among the possibilities that are known, a random copolymer is applied to the substrate, it being possible

So for the monomers of sald copolymer Lo be wholly or partly identical with those used In the block copolymer it is desired to apply.

Morsover, ii the wish 1s toe prevent, for exemple, the diffusion of the random copolymer, it 1g preferable to graft and/or crosslink the copolymer on the surface, throvgh the use of appropriate functionality. Grafting means the formation of a bond - a covalent bond, for

Hy examples Dotween fhe substrate and the copolymer.

Crosslinking means the presence of a plurality of bonds between the copolymer chains.

Among the various possibilities used for orienting the morphology of a block copolymer on a surface, a layer of a random PMMA/PS copolymer is applied beforehand to the surface.

Mansky et al. in Science, Vol. 275, pages 1458-1440 200 {7 March 1997), showed that a random poly (methyl methacryiate-co-styrene) (PMMA/PS) copolymer functional ized by a hydroxyl function at the chain end allows sifective grafting of the copolymer to the surface. The authors attribute the grafting capacity of these copolymers to the 23 presence of the terminal hydroxyl group originating from the Gnitiator; this constitutes a condensation grafting mechanism, which is not very effective from the standpoint of the temperature and times that are required, typically 24 to 48 nh oat 140°C, in this publication.

AU a cartain molar fraction of the methyl mathacrylabe and styrene (MMA and 3TY)] monomers, the interface snergles of a random copolymer with P33 and PMMA, respechbively, are

La. atrictly the same (Mansky et al., Macromolecules 1997, 30, 6810-6813). This situation arises in the case of a silicon support having a {ine oxide layer on the surface. In this case, this may present a drawback, since the ideal compesition of the random copolymer must axhiblt exactly this fraction in order for the interface energies with the

PS oand with the PMMA to be the same. When the composition of the random copolymer changes, the authors showed that a

PS-PMMA diblock copolymer applied to the random copolymer

HY may exhibit morphologies which are dependent on the composition of the random copolymer. It is therefore possible to change the morphology of the diblock cooolymer in the event of inconsistency of the MMA/STY fraction of the random copolymer.

More recently, certain authors (Han et al.,, Macromolecules, 2008, 9040-9097, Ji et al., Macromolecules, 2008, 80495- 9103, Insik In et al., Langmuir, 2006, 22, 7255-7360) have shown that Lt 13 possible, advantageously, to enhance the grafting of the random copolymer on the surface by introducing - no longer at the chain end but within the random copolymer itself - a plurality of functionalities such as hydroxyl cr epoxy. In this case, the copolymer is grafted by a plurality of functions on the surface (in the case of hydroxyl) and also crosslinked at the surface (in the case of epoxy).

Patent application US Z0080186234 considers the crossiinking of the random copolymer. This approach 1s also reported in numerous articles, including those of Ryu ef al., Macromolecules, ZG07, 40, 4726-4300; Bang J. et al.,

Adv, Mat., 2009, 21, 1-24, or else US 200903178001. With the use of crosslinkable random copolymers, as are widely used in the most recent approaches, a limitation becomes apparent when the desire is to neutralize a surface of given topography. The application of the random copolymer, followed by its crosslinking, completely covers the surface of given topography, which can no longer be exploited for itself, since the crosslinking prevents any removal of a part of fhe suriace which 1t 1s not desired should be covered, making this surface, so to speak, non-conforming.

When copolymers which are not crosslinked are used, it is 0 possible to remove the random copolymer which is at a drstance from the surface, being ungrafted, by the washing of the surface with an appropriate solvent, for example.

Therefore, following removal of this excess of copolymer, the initial surface topography 1s ragainad, the surface in this case being, so to speak, conforming.

Although the approaches previously described in the literature do allow certain controls over the orientation of a block copelymer on a surface Lreated with a random copolymer, a llmitation is apparent over the extent of the surface in question. This limits the industrial applications for Lhe purpose of cbtaining large surface areas of organized block copolymers, allowing in particular the production of materials for electronics at competitive cost.

Furthermore, these approaches require cimes OT temperatures, necessary for the graliting and/or crosslinking of the random copolymers, that are often prohibitive on an industrial scale.

Moreover, the surfaces treated with the random copolymers must, in the prior art, be prepared beforehand in accordance with specific protocols, and this complicates the application procedures.

The applicant has now found that the functionalized or non- functicnalized molecules which carry a covalent bond which is able to give rise to free radicals may advantageously he substituted for the copolymers used in the prior art, whether crosslinkable or not, and have numerous advantages, such as very vapid grafting or crosslinking times, a regularity of dispersion on the surface of the substrate, allowing the subsequent application of block copolymers with a morphology which 1s controlled and regular over large surface areas, and which avoids the laborious treatments of the substrate before being applied thereto, with effective grafting on numerous surfaces of different chemical origins. The applicant has alsc observed excellent control over the glze of the domains at scalss which may he substantially less than 20 nm. Lastly, the molecules, and more particularly the polymers or cepolymers, of the invention allow excellent preparation of surfaces having a topography which may subsequently form thes site of application of a block copelymer in accordance with a given orientation, while retaining the topography of the initial substrate.

Summary of the invention:

The present Invention relates to a surface preparation methed using molecules comprising at least one covalent bond which gives rise tc free radicals when the molecule is activated thermally, by organic or Inorganic reduction- oxidation, photochemically, by shear, by plasma, or else 3G under the influence of ionizing radiation, said method comprising the following steps: ~ contacting the molecules with the surface to be treated,

- activating the covalent bond which gives rise to free radicals thermally, by organic or inorganic reduction- oxidation, phetochemically, by shear, by plasma, or else under the influence of lenizing radiaticn, to form a film with a thickness of less than 10 nm and preferably 5 nm on the surface, - evaporating, when prasant, the saiubllisation or dispersion solvent employed for contacting the molecules with the surface to he treated.

H

Detailed description

By molecules are meant any electrically neutral chemical assembly of at least two atoms connected to one ancther by a covalent bond. This may be at least one small melecule, at least one macromolecules, O0r a mixture of molecules and macromolecules.

It is preferably at least one macromolecule, and more particularily at least one oligomer or at least one polymer or mixture thereof. More preferably, the assemblies in question are homopolymers or random, block, gradient or comb copolymers with a molecular mass by weight, measured by sire exclusion chromatography (SEC), of more than 500 g per mola,

The homopolymers or copolymers used in the method of the invention may be chtained by any route, including polycondensation, ring-opening polymerization, anionic or cationic polymerization or radical polymerization, the latter being controlled or not. When the copolymers are prepared by radical polymerization or telomerization, this process may be controlled by any known technigue, such as

NMP (Nitroxide Mediated Polymerization), RAFT (Reversible

Addition and Fragmentation Transfer), ATRP (Atom Transfer

Radical Polymerization}, INTFERTER {(Initiator-Transfer-

Termination), RITF (Reverse Iodine Transfer Polymerization) or LTP (lodine Transier Polymerization).

Preference will be given to those polymerization processes which do not involve metals. The copolymers are prepared preferably by radical polymerization, and more particularly by controlled radical polymerization, 2Ven mere particularly by nitrowide-controlled polymerization.

The molecules used in the method of the invention 0 correspond To the following general formula:

Rl A RZ

A is a covalent bond which gives rise to free vadicals, with a bond energy of between 80 and 270 kI/mol and preferably between 100 and 170 kJ/mol, av 25°C, measured 13 according fo the technlgue described by Kerr, Chem. Rev. 66, 465-500 (1260).

The bond in question is preferably a carbon-oxvgen bond of the kind found in alkoxyamines.

More particularly, the alkoxvamines derived from the stable free radical (1) are preferred.

Rp

Co N= O° (1) { { i

In this formula, the radical Ry has a molar mass of more than 15.0342 g/mol. The radical Ry may be a halogen atom such as chlorine, bromine or iodine, & saturated or unsaturated, linear, branched or ovelic hydrocarbon group such as an alkyl or phenyl radical, or an ester group -COOR or an alkoxy group -0OR, or a phosphonate group -PO (CR),

provided that iL has a molar mass of more than 15.0342. The radical Ry, which is monovalent, is said to be in P position relative to the nitrogen atom of the nitroxide radical. The remaining valencies cf the carbon atom and of the nitrogen atcem in the formula (1) may be bonded to various radicals such as a hydrogen atom, a hydrocarbon radical such as an alkyl, aryl or arylalkyl radical comprising from 1 to 10 carbon atoms. Tt is not impossible for the carbon atom and the nitrogen atom in the formulas

I (Ly to be joined to one another via a divalent radical, so as to form a ring. Preferably, however, the remaining valencies of the carbon atom and of the nitrogen atom in the formula (1) are bonded to monovalent radicals, The radical Ry preferably has a molar mass of more than 30 g/mol. The radical Ry may for example have a molar mass of between 40 and 450 g/mol. As an example, the radical Ry may be a radical comprising a phosphoryl group, it being possible for sald radical Ry to be represented by the formula: 2

Be

A oy — Pp — pf (2) i fl ¥ [B] = in which RY and R¥®, whlch may be identical or different, may be selected from alkyl, cycloalkyl, alkoxy, arvioxy, aryl, aralkyloxy, perflucroalkyl and aralkyl radicals and . Ce : = 3 4 3 may comprise from 1 to 20 carbon atoms. RY and/or RT may also be a halogen atom such az a chlorine or bromine or fluorine or iodine atom. The radical Ry may also comprise at least one aromatic ring, az for the phenyl redical or

LO the naphthyl radical, and the latter radical may be substituted, for example by an alkyl radical comprising from 1 to 4 carbon atoms.

More particularly, the alkoxyamines derived from fhe following stable radicals are preferred: - N-tert-butvl I-phenvi-Z-methylipropy]l nitroxide, - N-fert-putyl l-{(Z-naphthyli~-2Z-methylpropyl nitroxide, - N-tert-butyl Il-diethyiphosphono-2,2-dimethylipropyl nitroxide, ~ N-tert-butyl l-dibenzylphosphono-2,2-dimethylipropyl nitroxide, ~ N-phenvyl l-diethylphosphono-~2, 2-dimethylpropyl nitroxide, = N-pheny!l I—diethylphosphono~l-methylethyl nitroxide, - N-{l-phenyl-Z-methyloropy]l) l-diethylphosphono-1- methvylethyli nitroxide, - Ad-oxo-d, 2,0, 6-tetranathy i-l~piperidinyvloxy, ~- Z,4,6-tri-tert-butyiphenoxy.

Further to their bond energy, the alkoxyvamines used in controlled radical polymerization must allow affective contrel of the chain seguence of the monomers. Thus, they do not all allow effective control of certain monomers. For example, Lhe alkoxyamines derived from TEMPO do not allow control of more than a limited number of monomers, the same being true for the alkoxyamines derived from 2,2,5- rrimethyl-4d-phenyl~I-azanexnans J-nitroxide (TTPNO

Conversely, other alkoxvamines derived from nitroxides conforming to the formula (1), especially those derived from piltroxides conforming to the formula (2) and more particularly those derived from N-tert-butyl l-diethyvlphosphono~2, Z~dimethylpropyl nitroxide, alicw

S10 controlled radical polymerization to he extended to a large number oI monomers.

Moreover, the opening temperature of the alkoxyvamines also affects the economic factor. The use of low temperatures will be preferred in order to minimize the industr-ial difficulties. Preference will therefore be given to the alkoxyamines derived from nitroxides conforming to the formula (1), especialiv those derived from the nitroxides conforming te the formula (2), and even more particularly those derived from N-teri-butyl I-disthylphosphone-2,2- dimethylpropyl nitroxide, to those derived from TEMPO or 2,2, 5~trimethyl-4d-pheny]l-3-azahexane 3-nitroxide (TIPNO).

RI and RZ are at least two atoms which are different or not.

Preferably, Rl and RZ may be small molecules, or macromolecules, When Lthey are macromolecules, RL and RZ may be an oligomer or a polymer. More preferably, the species in question are, for RL, homopolymers or vandem or block, gradient or comb copolymers, with a molecular mass, measured by SEC, of more than 500 g/mol, and, for EZ, a molecular group with a mass < 1000 g/mol.

A gradient copolymer means a copolymer of at least two monomers wnich is obtained generally by living or pseudo- living polymerization. By wvirtue of these npethods of polymerization, the polymer chains grow simultaneously and therefore at each moment incorporate the same vatioz of comonomars, The distribution of the comonomers in Lhe polymer chains therefore depends on the profile, during the synthesis, of tho rolative concentrations oF he comonomers., Reference will De made to the following publications for a Theoretical description of gradient

S11 copolymers: TT. Pakula & al., Macromol. Theory Simul. 5, 887-1006 (19%6); A. Aksimetiev & al. J. of Chem. Physics 111, No. Z; M. Janco J. Polym. Sci., Part A: Polym. Chem. (20003, 38{(1%y, 2767-2778; M. Zaremski, & al. 3 Macromolecules (2000), 33(1Z2), 4365-4372; K. Matviaszewski & al., J. Phys. Org. Chem. (2000), 13(12}y, 775-786; Gray

Polym. Prepr. (Am. Chem. Soc., Div. Polym. Chem.) (2001),

AZ12y, 337-338; K. Matyiaszewskl, Chem. Rev. (Washington,

G.Ooy (2001), 10309), 2921-20G0.

The menomers whicn may be used for RI include the following:

For the Pracursors of polymers and copolymers bry i5 polycondensation: the Monomers used for premaring polyamides or copolyamides, polyesters or copolvesters, poliyesteramides or copolyesteramides, polyethers, polyimides, polvketcnes, polyether ketones, alone or in a mixture.

For the precursors of polymers and copolymers by anionic or cationic polymerization or by ring opening: vinyl, vinylaromatic, vinyiidene, diene, olefin, allyl or {(methlacryliic monomers, lactones, carbonates, lactams, lactides or giveolides, oxazolines, epoxides, cyclosiioxanes, alone or in a mixture.

For the precursors of polymers and copolymers by radical polymerization:

At least one winyl, vinylidene, diene, olefin, allyl or (meth)acrylic monomer. This monomar Ls solectsd more particularly from vinylaromatic monomers such as styrens or substituted Styrenes, especially alpha-methylstyrene,

S10. acrylic monomers such as acrylic acid or its salts, alkyl, cycloalkyl or aryl acrylates such as methyi, ethyl, butvi, ethylhexyl or phenyl acrylate, hydroxyalkyl acrylates such zs Z-hydroxyetnyl acrylate, etheralkyl acrylates such as

Z-methoxyethyl acrylate, alkoxy- or arvloxy-polyalkylene glycol acrylates such as methoxypolyethylene glyool acrylates, ethoxrypolyethylene glycol acrylates, methoxypolypropylene glvoel acrylates, methoxypolysetbthylens glycol-polypropyliene glycol acrylates, or mixtures thereof, aminocalkyi acrylates such as Z-{dimethylaminolethyl acrylate (DMAREA), flucerine-containing acrylates, silyl- containing acrylates, phosphorus-containing acrylates such as alkylene glycol phosphate acrylates, glyoidyl acrylates, dicvalopentenyloxyethyl acrylates, methacrylic monomers 13 such as methacrylic acid or lts salts, alkyl, cycloalkyl, alkenyl or aryl methacrylates such as methyl methacrylate (MMA), or lauryl, cyclohexyl, allyl, phenyl or naphthyl methacryiate, hydroxyaikyl methacrylates such as g-hydronyetnyl methacrylate or 2-hydroxypropyi methacrylate, etheralkyl methacrylates such as = ethoxyethyl methacrylate, alkoxy- or arvioxy-polyalkylasne giycol methacrylates such as methoxypolvethylene glvool methacrylates, ethorvpolyethylens glycol methacrylates, methoxypolypropylene glycol maethacrylates, methoxypolyethylene glyeol-polypropyleaene glycol methacryiates or mixtures thereof, aminoalkyl methacrvlates such as Z~{dimethylamino)ethyl methacrylate (DMAEMAYL, fluorine-contalning methacrylates such as 2,42 trifiuocroethyl methacrylate, silvi-containing methacrylates such as Z-methacryvloylpropyltrimethylsilane, phosphorus- contalning methacrylates such as alkylene glyeol phosphate methacrylates, hydroxyethyl imidarel idone methacrylate, hydroxyvethyiimidarzolidinone methacrylate, L={Z-ono=1-

S13. imidazelidinyl)ethyl methacrylate, acrylonitrile, acrylamide or substituted acrylamides, d=acrvioyl- morphaline, N-methyloclacrylamide, methacrylamide or substituted methacrylamides, N-methylolmethacrylamide, methacrylamidopropyltrimethylammonium chloride (MAPTACY, glyoidyl methacrylates, dicyolopentanyloxyetnyl methacrylates, itaconic acid, maleic acid or its salts, maleic anhydride, alkyl or alkoxy- or arvioxypolyalkylens glycol maleates Or hemimaleates, vinylpyridine, wvinylpyrrolidinone, {alkoxy)poly (alkylene glycol) vinyl ethers or divinyl ethers, such as methoxypolyl(ethviene glycol) vinyl ether, poly(ethylene giveol) divinyl eihsr, cilefinic monomers, inciuding ethylene, butene, hexene and l=octene, diene monomers, including butadiene, isoprene, is and also fiucrine-containing olefinic monomers, and vinylidene monomers, including vinyiidene fluoride, alone or ln a mixture of aft least two aforementioned monomers.

Ri is preferably a polymer, copolymer, oligomer or 26 cooligomer radical and RZ is preferably a nitroxy group.

With preference, RZ ig N-tert-butyl l-diethylivhosphono-2,2- dimethylpropyl nitroxide.

Rl 1s preferably a random copolymer with a molecular mass as measured by BEC using polystyrene standards of between 500 ¢ and 200 000 g/mol, more preferably betwsen 1000 and 000 g/mol, and even more preferably between 5000 and 10 000 g/mol, to give an application of copolymer by the method of the invention of less than 10 nm and more particularly less than 5 nm. The dispersity of RI, the ratio of the weight-average molecular masses Lo the number- average molaculary masses, is less than 5, more particularly less than 2, and preferably less than 1.5.

Cig.

Rl preferably consists of monomers among which mention may be made of styrene, methyl methacrylate, glyoidyl methacrylate (GMA), Z2-hydroxyethyl methacrylate {(HEMA}, methyl acrylate or =athyl acrylate. Styrene 1s pressnt preferakhly in the copolymer in molar amounts of from 40% fo 100% and more preferaply from 60% te &5%.

According to one preferred embodiment of the invention, the random copolymer of the invention 1s prepared with

Z-methvl-2-[ H-tert-butyl-N~ (diethoxyphosphoryl-2, 2- dimethylpropyviyaminoxy] propionic acid (RBleocbuilder MAY =

Arkema), styrene and methyl methacryiate.

The surface preparation method using the molecules of the invention 1g applicable to any surface and doss not necessitate particulary preparation, as 1s often the cage when the desire is to prepare a surface in order to apply to it a random copolymer for the purpose of a subsequent application of block copolymer exhibiting a regular 200 merpholiogy over a razrge surface area, without defects.

The surface 1s preferably mineral and more preferably is of silicon. Even nore preferably, the surface is of silicon having a native oxide layer.

According to one preferred embodiment of the invention, the block copolymers applied to the surfaces treated by the method of the invention are preferably diblock copolymers.

The method of the invention involves applying preferably the molecule dissolved beforehand in an appropriate solvent, by technlgues which ars known oe the skilled person, such as, for example, the fechnigus Known as spin

S15. coating, doctor blade, knife system or slot die system, although any other technigue may be used, such as dry application, in other words application without involving dissolution beforehand.

The method of the invention is aimed at forming a molecular layer of typically less than 10 nm and preferably less than 5 nm. When the method of the invention is used for preparing surfaces for the purpose of applying block copolymer, the molecule will preferably be a random {0 copolymer and the interaction energies with the two blocks of the plock copolymer or copolymers subsequently applied will be eguivalent.

The method cf the invention may be used in applications necessitating control of gurface energy, such as the application of hiock copolymers having a given nanostructuring, the enhancement of the printability of inks or of paint, of wettabllity, of weathering ocr ageing resistance, of adhesion, of biocompatibility, of prevention of migration of inks, or of prevention of the deposition of proteins, of selling or moulds.

Exampie 1: Preparation of & hydroxy-functionalized alkoxyamine (initiator Z) from the commercial alkoxyamine

BlocBuilder® MA (initiator 1):

A 1 1 round-bottomed flask purged with nitrogen is charged with: ~ 226.17 aq of BiocBuiider” Wa (initiator 1) {1 equivalent) - 68.9% go of Z-hvdroxyethyl acrylate (1 eguivalent) = b4E og of isopropanol.

The reaction mixture 1s heated at reflux (RBO°CY for 4 hours and then the isopropanol is evaporated under vacuum. This

S16 gives 287 g of hydroxy-functionalized alkoxvamine {initiator 2} in the form of a highly viscous vellow oil.

Example 2:

Experimental protocol for preparing copolymers from initiators 1, 2, 3 or 4, - Initiator 1 is the commercial allkoxvamine

BlocBullder® MA, - Initiator 2Z is the alkoxyamine prepared according to

Example 1. - Initiator 3 consists of a pair of reagents: azolscputyronitrile (ATEN) (1 molar eguivalent) and

N~tert-butyl l-diethylphosphono~2, 2~dimethylpropyl ] nitroxide {2 molar equivalents). - Initiator 4 is azolscbutyronitriie (RIBN).

A stainless steel reactor eguipped with a mechanical stirrer and a Jacket is charged with toluene, and also with the monemesrs such as styrene (5), methyl methacrylate (MMA, Z-hydroxyethyl methacrviate {HEMA]}, gilyvoidyl methacrylate (GMA), and the initiator. The mass ratios between the different styrene (35), methyl methacryviate (MMA), Z-hydroxyethyl methacrylate (HEMA) and glvyveidyl methacrylate (GMA) monomers are described in Tahkle 1. The mass charge of toluene 1s fixed at 30% relarvive to the reaction mixture. The reaction mixture 1s stirred and

S17. degassed by sparging of nitrogen at ambient temperature for 30 minutes.

The temperature of the reaction mixture is then raised to 115°C (in the case of the polymerizations carried out in the presence of initiators 1, 2 and 3) or 75°C (in the case of the polymerizations carried out In the presence of initiator 4). The time t=0 begins at ambient temperature.

The temperature is held at 115°C or 75%°C throughout the polymerization, untll a monomer conversion of the order of

HO 70% ds attained. Samples are taken at ragular intervals in order to determine the kinetics of polymerization by gravimetry (measurement of dry extract).

When the conversion of 70% 1s attained, the reaction mixture is cooled to 50°C and the solvent and residual monomers ara evaporated under Vacuum, Following evaporation, methyl athyl ketone is added to the reaction mixture in an amount such as fo produce a copolymer solution of the order of 25% by mass.

This copolymer solution is then introduced dropwise into a beaker containing a non-solvent (heptane), in order Lo precipitate the copolymer. The mass ratio between solvent and non-sclvent (methyl ethyl ketone/heptane) is of the crader of 1/10. The precipitated copolymer is recovered in the form of a white powder after filtration and drying.

S18

Initiai reaction state Characteristics of the copolymer tnitiat composition . Le by mass of the Nature of Ratio by mass of initiator " - - - . initiator relative to the monomers %hPS Mp Mn © Mw ip

Copolymers monomers used S, MMA, HEMA and GMA

SMMAHEMA/GMA

TT

I I re ee ee] eT ee ee eee ee eee

Te ee ee ee eT ee

Takile 1 3 zy Determined by size exclusion chromatography. The polymers are dissolved at 1 g/l in THF stabilized with BHT,

Callbration is carried out using monodisperse polystyrene standards. Double detection by refractive index and UV at

W254 nm makes it possible to determine the percentage of polystyrene in Lhe copolymer.

Apart Irom the copolymers described in Example 2, the block copolymer PS-b-PMMA (PS 46.1 kg.mol™’, PMMA 21 kg.mol™, PBDI @ 1.08) was purchaszsd from Polymer Source Inc. (Dorval, guebec) and used without subpseguent purification.

Grafting on 510;:

Bilicon plates (crystallographic orientation { 100) are cut rv hand into pleces measuring 3 x 4 cm and are cleaned by piranha treatment (H:S0,/H.0. 2:1 {vrvh) Lor 1% minutes, then rinsed with deionized water and dried in a stream of nitrogen just before functionalization., The remainder of the procedure is as described by Mansky 4 al. (Science, 15497, 1458), with a single modification (baking takes place in ambient atmosphere and not under vacuum. The random copolymers are dissolved in toluene to give solutions at 1.9% by mass. A sclution of PS-r-PMMA is dispensed by hand on to a freshly cleaned wafer, then spread by spin coating at G0 rpm, to give a film with a thickness of approximately 20 nm. The substrate is then simply placed on a hotplate, brought beforehand to the desired remperature, under amblent atmosphere for a variable time. The substrate

Ls then washed by sonication in a number of toluene baths for a few minutes in order to remove the ungrafted polymer from the surface, and then is dried under a stream of nitrogen.

Grafting on gold:

The gold substrates used consist of polyerystalline gold and are manufactured as follows: a thermal silica layer is first appiied to an Si surface (100 nm), and then a tie

Laver of chromium (~10 nm) is evapcrated on to the surface, and finally a laver of ~500 nm of gold is evaporated on to the substrate,

- 2H)

The gold surfaces are cleaned with an oxygen plasma for minutes, and then the gold oxides formed are reduced by a bath in absolute ethanol for 20 minutes, and the surface 1s dried under a stream of nitrogen (HEH. Ron & &l., Langmuir, 5 19%&, 1116). If the use of plasma 1s not desired, the gold surfaces may simply De washed by sonication in a bath of apsolute ethanol and then a bath of toluene for 10 minutes, and then dried under a stream of nitrogen.

The procedure followed for grafting the polymers on Lo gold [0 is the same as that for the silica surfaces.

Characterisations:

The XPS measurements were carried out on a personalized 220 1 spectrometer from VG Scientific; the spectra were obtained with an X-ray source calibrated to the Ko ray of aluminium (1486.06 eV). The film thickness measurements were performed on a Prometrix UVIZEB0 ellipsometer. The images obtained by scanning electron microscopy were recorded on a

Co-S5EM HS3G0 from Hitachi,

In this example, a comparison is made of the morphology ohserved for the self-assembly of the cylindrical Dbicck copolymer (PS-h-PMMA) of Example 3 when it is applied to an untreated silicon surface (Figure 1h}, resulting in a parallel orientation of the block copolymer relative to the surface, or no a surface treated according to the method of the invention, using the vandom copolymer 5 of Table 1, and

Leading to a perpendicular orientation of the block copolymer relative to thes surface (Figure 1B).

S21

In this example, a comparison is made of the morphology chserved [for the self-assembly of the coylindrical block copolymer (P5-b-PMMA) of Dxample 3 when it 1s applied to a cleaned polyeorystalline gold surface but in the absence of copolymer of the invention (Figure 2A), resulting in a parallel and perpendicular orientation of the block copolymer relative £0 the surface, to a cleaned polycrystalline gold surface treated according to the

Wo method of the invention, using the random copolymer 5 of

Table 1, and resulting in a perpendicular crientation of the block copolymer relative to the surface (Figure 2B), or to an uncleaned polycrystalline gold surface treated according to the method of the invention, using the random copolymer 5H of Table 1, and resulting in a perpendicular orientation of the block copolymer relative to the surface {Figure 20). in this example, a comparison 1s made of the morphology chserved for the self-assembly of the cylindrical block copolymer (PE-h-PMMAY of Example 3 when it ls applied to a silicon surface treated according Lo the method of the invention, using the random copolymers 1, 2, 3, 4, 5, 12, te, 18 and 19 of Table I (Figures 3A, 3B, 3C, 3D, 3, 3F, 3G, 3H, 31), for which the composition varies in terms of styrene. It will be noted that a maximum of perpendicular 3 orientation of the block copolymer is situated when the composition of the random copolymer in terms of styrene is in the range of 75-85%,

S07

Example 7:

In this example, a comparison 1s made of the morphology chserved for the seli-assembly of the oylindrical block copolymer (P3-bL-PMME) of Example 3 when it is applied to a gilicon surface treated according to the methed of the invention, using the random copolymers 11 and 17 of

Table 1. It will be notsad in particular therein that ithe presence of acid and alkoxyamine function in the copolymer 6 11 of Table 1 or the absence of any function other than the stkoxvyvamine of copolymer 17 in Table 1 leads to the same result (Figures 4k and 4B).

In this example, an observation Lis made of the morphology observed for the self-assembly of the ovlindrical block copolymer (PS-h-PMMAY of Example 3 of the invention when it is applied to a silicon surface treated with the randon copolymer 19 of Table 1 (Figure 5A) or 20 (Figure 5B), resulting in a parallel orientation of the block copolymer.

In this example, a comparison 1s made of the grafting kinetics of copolymers 5 and 11 of Table 1, applied to a silicon surface Lreated according toe the method of the invention (Figure §, thicknesses normalized). By normalized thickness, Li la considered that the maximum thickness attained by each polymer 1s 100%.

It will be noted that, In spite of the absence of hydroxyl function in the copolymer 11 (PE-r~-PMMA}, the same grafting

Kinetics are observed as {or the copolymer 5 (P5-PMMA-OH) .

Example 10:

In this example, a comparison ls made of the grafting kinetics of copolymers 3, 8 and 9 of Table 1, applied to a silicon surface treated according te the method of the invention. It will be noted that there 1g little influence of the molecular mass on the grafting kinetics (Figure TA and TB).

In this example, an observation ig made of the morphology observed for the self-assembly of the cylindrical block copolymer (PS-b-PMMA) when it is applied to a silicon surface treated with Example ¢ of Table © (Figure BA) and

Example 14 of Table | (Figure BB), resulting in a perpendicular orientation of the block copolymar.

Figure $ shows the thickness profile of the applied film of copolymer 14 as a function of the temperature.

Claims

Lad. CLAIMS

1. Surface preparation method using molecules comprising att least one covalent bond which glves rise to free radicals when the molecule is activated thermally, by organic or inorganic reduction-oxidation, photochemically, 1 - 1. hu} - h - - don Ge, : or en . . - = bbw shear, by plasma, or else under the influence of ionizing radiation, said method comprising the following steps: 0 - contacting the molecules with the surface Lo be treatad, - activating the covalent bond which gives rise to fres radicals thermally, by organic or inorganic yeduotion-— oxidation, photochemically, by shear, by plasma, or else under the influence of lonizing radiation, to form a film with a thickness of less than 10 nm on the surface, - evaporating, when praesent, Lhe solubilization or dispersion solvent emploved for contacting the molecules with the surface to De treated.

£. Method according to Claim 1, wherein the covalent bonds which give rise to free radicals have a bond energy of between 20 and 270 kF/ mol.

I. Method according toe Claim 1, wherein the covalent I5 bonds which give rise to free vadicals have a bond energy of between 100 and 170 kJ/mol.

4. Method according to Claim 1, wherein the molecule 1s a polymer, HL Method according to Claim 1, wherein the molecula 1s a copolymer,

L25 a 5 te} co pg pot on Le - ed fon a 3 Ym ny mT rrr es ve Ae

6. Method according te Claim 5, wherein Lhe copolymer is a random copolymer.

I. Method according to Claim 5, wherein the copolymer is a gradient copolymer.

i. 2 = be oy od Sy pre A oye i Cys i -~ i rb pn i Fr 8, Method according to Claim © or 7, wheraeln the - - Torrey 1 Pom em = o men | “ non ag ge - ps A Gen ame oor - vey] copolymer has a molecular mass of more than 200 g/mol. - 0 fon, de Tm pm wy on ged dg Ge NY mn pe oo a. 1 lem en ee i Ge Ho “. Methed according to Claim 60 or [a wherein Fhe copolymer has a molecular mass of between 1000 and TET ee Sree 20 G00 o/mol,

18. Method according to Claim © or 7, wherein the 15 copolymer 1s prepared by controlled radical polymerization.

11. Merhod according to Claim 6 or 7, wherein the copolymer 1s prepared by nitroxide-controlled radical E 7 k k 2 polymerization. 20 Ty Ten dm 3 3 mu pm ce a pn nd pr pr fo pa, SRE TE TY wor mn en a ye Ln ee pen A pd pen gm

12. Method according to Claim 11, wherein the nitroxides conform to the formula below: 28 ee Con Nm O° (1 j Anownioh the vadical Ry has a molar mass of more than de NAT LDU 3 da. EE] Bf om den hen on pd tv pros gong pon od qe om fr Ton dg EE nT eh So he on eT a da

14. Method according to Claim 12 ’ Ween Lite LOL LOWLNG nitroxides are preferred:

= N-Lert-butyl l-phenyl-2-methylpropyl nitroxide, = N-terf-butyl l-{Z-naphthyl)-2-methylpropyl nitroxide, - N-tert-butyl Il-diethylpheosphono-2,2-dimethylipropyl nitroxide, - N-tert-butyl l-dibenzylphosphono-2,2-dimethylipropyl nitroxide, - MN-phenyl I-diethylphosphono-2, 2-dimethyipropyl nitroxide, = Nephenyl L-diethylphosphono-ti-methylethyl nitroxide, - Ne (L-phenyl-Zd-methylpropyl) l-diethylphosphono-1- methylethyl nitroxide, = d-oxo-2,2,6,0~tetramethyvl-i-piperidinvioxy, 3 = 2,4, e-tri~terit-butviphenoxy.

14. Method zccording to Claim 13, wherein the nitroxide ig H-tert-putyl l-diethylphosphono-2, 2-dimethylpropyl nitroxide. 20

15. Copolymer used for implementing the method according to Claim 1, characterized by the product of synthesis of methyl methacrylate, of styvrane and of Z-wmethyl-Z- H-tert- butyi-N-(diethoxyphosphoryl-2, 2dimethyvipropyvl) aminoxy] - propionic acid.

16. Method according to any of Claims 1 to 14, wherein the surface 1s mineral.

17. Method according to any of Claims 1 to 14, wherein the surface 1s metallic.

18. Method according to Claim 16, whereln the surface is of silicon.

L327

19. Method according to Claim 17, wherein the surface 1s gold.

20. Use of the method according to any of Claims 1 to 13 tor contrelling the structuring of block copolymers, ennancing The printabkility of inks Gr paint, the wettabhlliity, the weathering or ageing resistance, the adhesion, the biocompatibility, the prevention of migration of inks, the prevention of deposits of proteins, of soiling or of moulds,